1. Field of the Invention
The present invention relates to a combination indicator apparatus for an automotive vehicle provided with a plurality of indicators, and more specifically to a combination indicator apparatus for an automotive vehicle which can indicate various information related to an automotive vehicle, such as vehicle speed, engine revolution rate, coolant temperature, fuel quantity, etc.
2. Description of the Prior Art
An example of prior art combination indicator apparatus is shown in FIG. 1, in which a speed meter 1, a tachometer (engine speed meter) 2, a coolant temperature meter 3, and a fuel meter 4 are incorporated in combination. The vehicle speed meter 1 is of the electromagnetic indication type, which comprises a rotary shaft 1a rotated by a vehicle wheel shaft linked to a transmission, a cylindrical magnet 1b fixed to the rotary shaft 1a, and an induction cap 1c magnetically coupled to the cylindrical magnet 1b. Therefore, when the cylindrical magnet 1b is rotated by the rotary shaft 1a at a rotary speed proportional to vehicle speed, since electromagnetic induction force according to the vehicle speed is generated between the magnet 1b and the induction cap 1c, the induction cap 1c is rotated and therefore a pointer 1d fixed to the induction cap 1c is rotated on a vehicle speed dial 1e to indicate vehicle speed.
The tachometer 2 comprises a period/voltage converter 2b for receiving a signal synchronized with an engine ignition signal via a signal wire 2a and outputting a signal whose voltage level is inversely proportional to the period of the ignition signal, and a movable coil movement 2c driven by the output signal from the period/voltage converter 2b. Therefore, when the movable coil movement 2c is energized, a pointer 2d fixed to the movable coil movement 2c is rotated on an engine speed dial 2e to indicate engine revolution rate.
The coolant temperature meter 3 comprises a cross-coil movement having two cross coils 3a and 3b and a magnet rotor 3c driven by the cross coils 3a and 3b when energized. The first coil 3a is energized by a current supplied from a supply voltage + and the second coil 3b is energized by a current applied from a coolant temperature sensor (not shown) via a signal wire 3d and proportional to coolant temperature. Therefore, the magnet rotor 3c is rotated by a resultant magnetic field generated by the two cross coils 3a and 3b, so that a pointer 3e fixed to the magnet rotor 3c is rotated on a temperature dial 3f to indicate coolant temperature.
The fuel meter 4 comprises a cross-coil movement having two cross coils 4a and 4b and a magnet rotor 4c driven by the cross coils 4a and 4b when energized. The first coil 4a is energized by a current supplied from a supply voltage + and the second coil 4b is energized by a current applied from a fuel sensor (not shown) via a signal wire 4d and proportional to the remaining fuel quantity. Therefore, the magnet rotor 4c is rotated by a resultant magnetic field generated by the two cross coils 4a and 4b, so that a pointer 4e fixed to the magnet rotor 4c is rotated on a fuel dial 4f to indicate the quantity of remaining fuel.
The above-mentioned four indicators are housed within a single casing 5 to construct a combination indicator apparatus for an automotive vehicle. Further, various sensor signals detected by sensors (not shown) are directly applied to the indicators to indicate various information.
In the above-mentioned prior art combination indicator apparatus, however, since the operating principles of the indicators are different from each other, different technology has been required for improvement in performance and productivity of the indicator. Therefore, the development cost required for the product and the manufacturing equipment is not concentrated, thus resulting in an increase of the apparatus cost.
In addition, since different indicators are actuated in different ways, different signal wires must be arranged therefor; it has been difficult to reduce the number of signal wires, and therefore a wastefull space is required for the vehicle, in particular, at the cowl portion at which a great number of wires are arranged. Further, since the movements of the indicators are different from each other in structure and shape, a large or complicated shape is required for the casing. In addition, since the troubleshooting methods are also different from each other, it takes much time to troubleshoot and repair these indicators, in different ways.